1. Field of the Invention
The present invention relates to a strip for winding around and gripping an elongate object, and to a kit of parts for forming such a strip. The elongate object may, for example, be one or more cables (especially telecommunications cables), wires, optical fibres or the like, or it may be one or more tubes or pipes or the like.
2. Brief Description of the Background Art
In the art of cable splice closures, it is known to wrap tape around a cable in order to build up its diameter to that of a cable entry port of a splice closure, in order to seal the closure. For example, U.S. Pat. No. 4,933,512 discloses a cable junction closure comprising a sleeve, a pair of rigid end plates for closing the spaces between the cables and the sleeve, an elastic tape wound around the cables for sealing any gaps between the cables and the rigid end plates, and an elastic tape wound around each rigid end plate for sealing any gaps between the end plates and the sleeve.
U.S. Pat. No. 5,124,507 comprises a sleeve, sealing members with cable passage openings for insertion in the ends of the sleeve, and semi-circular sealing elements in the form of individually removable bearing shells lining the cable passage openings of the sealing members, for adapting the openings to different cable diameters. In order to eliminate any air gaps between the cable and the surrounding bearing shells, a sealing tape or band is wound onto each cable.
U.S. Pat. No. 5,346,742 discloses a sealing tape for winding around a cable leading through a cable passage opening, to form a seal which fits between the cable and the cable passage opening. The inside of the tape facing the cable has a roughened surface to increase the friction between the tape and the cable. The roughened surface is formed by projecting friction elements, which may be made from fine-grained carborundum or emery embedded in an adhesive layer, or from metal or plastic teeth anchored in the material of the tape.
Co-pending International Patent Application No. PCT/GB95/02229 (Raychem) discloses a retention strip for winding around an elongate object, which when so wound in use can decrease in length when compressed around the object, thereby allowing contraction of the strip around the object. The entire disclosure of PCT/GB95/02229 is incorporated herein by reference. This international application, which is assigned to the assignee of the present invention, describes a retention strip for an elongate object, which retention strip is related to the present invention. The retention strip is particularly useful for retaining a cable because the strip can decrease in length when compressed around an object.
The retention strip typically contracts by the correct amount at each part of the circumference of a cable, as it comprises one or more, preferably a plurality, of collapsible portions, and decreases in length due to the collapsing of these collapsible portions, as needed. Preferably the collapsible portion can collapse by deforming, e.g. by being crushed or concertinaed or by buckling. Preferably, such deformation occurs in a direction generally or substantially parallel to the (axial) direction of extension of the elongate object around which the strip is wound. Each collapsible portion of the strip preferably comprises a relatively weak portion of the retention strip. More preferably, each collapsible portion comprises one or more webs extending between substantially non-collapsible portions, e.g. one or more relatively thin portions which can deform by buckling or concertinaing, for example.
The retention strip may be profiled such that, when spirally wound around an elongate object in use, successive windings interlock with each other, thereby substantially preventing helical displacement of the windings with respect to each other along the object. The retention strip may, for example, have a plurality of protrusions and recesses which can engage with each other when the strip is wound in use. More preferably, each substantially non-collapsible portion (where present) of the retention strip has one or more projections on one surface thereof and one or more cooperating recesses on the opposite surface thereof, such that, for example, when the strip is wound around an object, the projection of one non-collapsible portion fits together with the recess of another non-collapsible portion with which it overlaps, or by which it is overlapped.
The retention strip may be used as part of a cable splice closure, where it is used in combination with a housing and a compressing means to compress the retention strip around a cable extending, in use, into the housing. Further, the cable splice closure may also include at least one sealing member to form a seal between the housing and one or more cables extending into the housing. Each sealing member may have one or more cable entry apertures in which at least one retention strip may be located. Preferably, when the retention strip is contracted around a cable in a cable entry aperture through which the cable extends, the retention strip can grip, and thereby retain the cable in the aperture. Preferably the ends of the cable splice closure are sealed using such a sealing member.